I was hoping it wouldn't find me but it did.A little history:This is my 2nd summer with this car.Beginning last summer everything worked find. By the end of last summer all the air was coming out of the floor and defrost vents,which is common for the 96.The air was ice cold,so I could live with that.Got it out last week now nothing but hot air.The compressor is not engaging.
I've done some searches and found lots of write ups on this subject.So those thats been down the 1996 A/C road any advice?

 

Refrigerant and have the system evaluated - it ain't a '96 thing

 

R134a has tiny particles. Bottom line is every system leaks, even in fairly new cars. There is a low pressure switch that deactivates the compressor so you don't burn it out when the pressure is low. Go to your local wal mart, pep boys, etc. and pick up a can of 134a with the tube attached and follow the instructions. If you have other cars that are more than 3 years old get a second can to top them off too. I do all my cars annually when the summer starts and they all take at least a little every year.

 

Mine was leaking in the condenser after I replaced all those O-rings, which age and leak more; not a huge job for most of it.

UV light will indicate leaks, in a darkened environment, perhjaps as well as a sniffer.

 

Either the low pressure switch or the high pressure switch if not happy can shut down the compressor. The low pressure switch may not be closing and be defective and cause the compressor not to run. It can be jumped out in which the compressor would start if all else was OK and the switch was bad.

You really can't add Freon to a system if the compressor is not running for a number of reasons. If you do not have a set of gauges you are really in the dark as to what's going on. Trying to add Freon to a system that is not running will usually do nothing except if the system is totally empty and I rather doubt that. (It does not take much to close the low pressure switch).

If your skill level is weak and with no gauges going to a AC shop would at least give you a start and usually a check out if of no cost.

If the system has Freon and even a low charge, there could be a number of electrical reasons why the compressor is not running.

For your vent problem I would first check the 3 hose check valve under the right side plastic engine cover to see if it is cracked or broken. It's a common part failure for vent problems as yours.

 

Your vent problem may be the three way valve but in all likelihood it's the programmer on the firewall above the gas pedal. There are lots of threads on it.

Here's one of the better threads -
https://www.corvetteforum.com/forums...l-problem.html

BTW, I used the 7/64 tubing and bypassed the connector to fix mine - working fine for 4 years now.

On the C68 electronic in dash head unit, you can put it into diagnostic mode and read any trouble codes. Here's a link to how to do it -
http://www.corvetteactioncenter.com/...codes-723.html

Here's a Youtube video showing how to do it -

If you don't already have it, pick up a Factory Service Manual (FSM), it will be a great help in diagnosing this and other problems.

Good luck.

 

Where is the A/C relay located?I detailed the engine(no water) last week for a car show.Could have knocked a connector loose?
Thanks folks for all the great information...

 

Checked codes ---no codes.

 

Pull the service caps off and spit in the valves look for bubbles. You can replace the valves without loosening freon or get new caps will help. Add some freon if low the compressor will start kicking on.

 

Without a gauge you can't tell if Freon is low. You can't tell how much Freon is in a system in relation to pressure. Because these refrigerant gases have a specific pressure in regard to temperature as to why there are temperature/pressure charts.

In order to replace a Schrader valve a special tool is needed so no gas is lost but that’s only if the valve is determined to be bad. On the vette only the low pressure valve is a Schrader valve. The high pressure valve is a ball valve. The whole valve assembly has to be unscrewed and removed to change the valve and in order to do this the system has to be evacuated and then refilled.

Most of these procedures require a higher skill and special tools. It's not like Joe Blow adding Freon to a working system.

 

Assuming that you don't have a set of R134 gauges - you could stop by a big box sore and buy a R134 A/C Recharge rig that has the gauge on it (typically these run about $20 or so). When you hook the can to the car - the gauge on that set-up will read what the low side pressure is... If it reads 0 - you have effectively lost all of your Refrigerant, and you'll need to find & repair the leak. If there is pressure in the system - you can try to add a little bit of R134 and see if that's enough to get the compressor to turn on. As previous posters have pointed out - it doesn't take a ton of Freon in the system to get the compressor to at least turn on for a little while. If the Freon is low - the compressor will cycle off quite quickly. Again - without the compressor running - the pressure in the system is dependent on temp, and the pressure will be equal on the low side and high side. When the compressor cuts in - the pressure on the low side drops, and if the refrigerant level is low - it will drop very quickly and to a very low level - and the low pressure switch will switch the compressor back off.

I would HIGHLY recommend trying to find a can of Refrigerant with a pressure gauge AND with a UV dye mixed in the refrigerant. That way - if you can get the system to run even for a little while - the leak will be relatively easy to find with a blacklight.

 

I'II add this:Last nite while I was putting the car in garage.The temp reached hotter enough to engage cooling fans.When fans went on the compressor engaged for a split second.Did this several times.I'm sure that means something to the experienced.

 

When the compressor came on did it blow cold?

 

It being like one sec.so it was cool air,not hot.But,it was 58-60 degrees in the garage.

 

Sounds like it just needs freon. I just add it slowly and the compressor will kick on longer and longer. Once it runs full time keep checking the line often. It will be cold once it does a cold flash it is good. Do this when it is hot outside windows open and max cold. It might kick off a bit if it is cold enough.

 

Get yourself a diy set of a/c r134a brass manifold gauges and the FSM. Chapter 1B of the FSM has a detailed and easy to follow diagnostic of the HVAC system.

Here's a decent gauge set -

Otherwise best to take it to an a/c specialist.

 

I wrote up a controller fix w/pics shortly after I bought my Grand Sport back in '06 - search repair topics on this site.
You have two problems - the controller nipples collapsing (cold air coming out of lower vents) and obviously the no a/c problem which may just be low freon. Buy a $36 recharge can at your local auto parts store and see if that gets you cold air, then repair the controller - it's not difficult at all.

 

Harbor Freight also has gauges for about same price but there is always a 20% coupon.

Let me just add that if the low pressure switch is not closed due to the Freon charge being so low, that would probably indicate a large leak where the system is near empty. If you do add Freon and the compressor does kick on and runs, this would verify almost no gas in the system.

Let me also go on the negative and say that if the system is full and compressor not running, the static pressure at the low pressure port can be 70 to 110 psi (system equalized). When you connect a can of Freon it may pressurize the can and cause it to explode the relief cutout at bottom of can. This is likely not to happen but can be a bit dangerous and just want you to be aware of this. This is why you use a gauge.

Digital Disaster - has a really good write up on the nipples and fix if this is the repair that needs to be done.

 

Are you sure!

Did you interrogate both the HVAC programmer, as well as the PCM?

Codes 66-69 and possibly code 70.. will disable the A/C as well! If you in fact have "No" codes present then the refrigerant level is probably OK and there is a wiring issue. Or as you stated a problem with the Relay.

http://tech.corvettecentral.com/2011...trouble-codes/

This is a picture out of an 95 FSM

 

one more thing; Have you checked your A/C Clutch fuse for signs of heat damage, Blown etc.